1. Field of the Invention
This invention relates to a magnetic tape wind-up method for winding up a magnetic tape around a hub, which is incorporated in a cassette case, while the magnetic tape is being moved and is in contact with a contact member, such as a guide pole, provided in the cassette case.
2. Description of the Prior Art
Tape cassettes such as video tape cassettes comprise a cassette case, a pair of reel hubs which are provided in the cassette case, and a magnetic tape which is wound around the reel hubs.
Various methods have heretofore been used to assemble the tape cassettes. One of such methods, a V-O method, is disclosed in, for example, Japanese Unexamined Patent Publication Nos. 55(1980)-77057 and 62(1987)-106377. With the V-O method, instead of a magnetic tape first being wound around a pair of reel hubs and then the reel hubs being incorporated into a cassette case, a pair of reel hubs connected to each other by a leader tape are first incorporated into a cassette case. Thereafter, the leader tape is pulled out and cut, and an edge of a magnetic tape is joined to one of the cut edges of the leader tape. The reel hub having the leader tape portion joined to the magnetic tape is then rotated and winds up the magnetic tape.
However, in the cassette case a contact member, such as a guide pole, is provided, and it comes into contact with the magnetic tape when the magnetic tape is moved. Therefore, with the aforesaid method for winding up a magnetic tape around a reel hub incorporated in the cassette case, as the magnetic tape is wound up around the reel hub and is moved into the cassette case, a magnetic surface thereof is in contact with the guide pole. As a result, problems described below arise when the magnetic tape is quickly wound up in order to shorten the time required to produce the tape cassettes.
First, in cases where the magnetic tape is moved quickly while it is in contact with the guide pole, tension on the magnetic tape is lost or fluctuates because of resistance between the magnetic surface of the magnetic tape and the surface of the guide pole. Therefore, it is not always possible to wind up the magnetic tape reliably around the reel hub.
Also, in cases where the magnetic tape is wound up quickly around the reel hub, the magnetic surface of the magnetic tape rubs against the surface of the guide pole. As a result, a magnetic layer on the magnetic surface is separated from the magnetic surface, which causes drop-outs to arise during magnetic recording and reproduction.
Moreover, side edges of the magnetic tape have burrs depending on how the magnetic tape was cut from a magnetic tape web in the process used to make magnetic tapes. When the magnetic tape is moved quickly while it is in contact with the guide pole, burrs are separated from the side edges of the magnetic tape and appear as white powder, which accumulates on the guide pole. The white powder moves from the guide pole to the magnetic tape and clings thereto when the magnetic tape is moved during magnetic recording and reproduction. The white powder on the magnetic tape generates drop-outs.